SpaceX on Thursday postponed the planned launch later this week of its unmanned Dragon cargo ship after unspecified "issues" arose during a launchpad test, the company said in a statement.

The launch of the Dragon atop the Falcon 9 rocket, initially set for Friday, will now take place no earlier than January 6, SpaceX said.

"The new launch date will provide SpaceX engineers time to investigate further issues that arose from a static fire test of the Falcon 9 rocket on Dec. 16," it said, without elaborating on what the problem involved.

Right after the launch, the California-based aerospace firm aims to attempt its first precision ocean landing of the first stage of the Falcon 9, setting it down on a floating platform instead of letting it fall into the ocean.

SpaceX is trying to revolutionize the aerospace industry and make rockets more like airplanes which can be used over and over.

"Stabilizing the Falcon 9 first stage for reentry is like trying to balance a rubber broomstick on your hand in the middle of a wind storm," said a company statement.

"However this test represents the first in a series of similar tests that will ultimately deliver a fully reusable Falcon 9 first stage."

The postponement until January of the company's fifth contracted flight with NASA to resupply the astronauts at the International Space Station will not harm the goods being carried or leave the people in space short of food or supplies, it said.

"The launch postponement has no impact on the station's crew or its complement of food, fuel and supplies and will not affect the science being delivered to the crew once Dragon arrives at the station."

The launch on Tuesday, January 6 is scheduled for 6:18 am (1118 GMT), with the cargo vessel arriving on January 8 at the orbiting outpost.